I see,
each customer should be accommodated with a party
in ax2012 entities are treated as parties such as vendor, customer, worker, legal entity, etc. all are treated as party
in short each customer should must have a record in dirpatytable.
possibly you need to fix your data. we cannot throw a more detailed answer, as you have access to your system
for experiment purpose take any record which exist in CustTable and is not appearing in list to user. create a corresponding record in dirPartyTable and update party information for this record in customer master. now observe number of records